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The CLIVAR International Climate of the Twentieth Century (C20C) Project

West African Monsoon Modeling and Evaluation (WAMME) Workshop - 20 January 2008 - New Orleans. The CLIVAR International Climate of the Twentieth Century (C20C) Project. Chris Folland, Hadley Centre, Met Office & Jim Kinter, COLA. 1. History and aims 2. Methodology and approach

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The CLIVAR International Climate of the Twentieth Century (C20C) Project

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  1. West African Monsoon Modeling and Evaluation (WAMME) Workshop - 20 January 2008 - New Orleans The CLIVAR International Climate of the Twentieth Century (C20C) Project Chris Folland, Hadley Centre, Met Office & Jim Kinter, COLA 1. History and aims 2. Methodology and approach 3. Forcing data sets 4. Some achievements 5. Continuing development of C20C

  2. Purpose and basic methodology • Purpose: Characterize variability, trends and predictability of climatic conditions and events of the past ~130 years associated with slowly varying forcing functions including SST • Initially focused on AGCMs all forced with same HadISST sea surface temperature and sea ice analysis • Differs from AMIP in NOT being primarily focused on model validation and with strong multi-annual to multi-decadal variability (predictability and understanding aspects) focus • AMIP: only ~20 years • C20C: ~130 years

  3. Approach • Period of interest: 1871-current • Organization: • Jointly organized by Hadley Centre, UK & Center for Ocean-Land-Atmosphere Studies (COLA), USA • 28 different modelling groups participating/affiliated internationally • CLIVAR project & reporting to WMO/CAS/WGNE • Now includes many other forcing data sets, including greenhouse gases, ozone, volcanic aerosols and solar variability • Expanded to include use of “Pacemaker experiments” and coupled models in order to more accurately simulate modes of variability that are inherently coupled, and to understand mechanisms

  4. Contributions of C20C C20C contributes to: • Seasonal to interannual predictability • Decadal to interdecadal variability & predictability • Understanding climate trends • Model evaluation

  5. Chronology • Project initiated by Hadley Centre 1993 • several informal bilateral collaborations established • 1st workshop - Hadley Centre Nov 1994 • input to 1995 IPCC Assessment chapter “Climate Models – Evaluation”. • special session at 1st international AMIP conference in 1995 Revitalized in 1998-9 through infrastructure provided by COLA (www.iges.org/c20c; GDS) • 2nd workshop - COLA Jan 2002 • reported in CLIVAR Exchanges, Jun 2002 • agreed set of runs, updated forcing data sets, diagnostics and special projects

  6. Chronology C20C established as official CLIVAR project in January 2003 • 3rd workshop - 19-23 Apr 2004, ICTP, Italy • Special meeting - 4-5 July 2005, Prague, Czech Republic • reported in CLIVARExchanges, Oct 2006 • 4th workshop - 13-15 March 2007, Hadley Centre, UK • reported in CLIVAR Exchanges, Jan 2008

  7. Phases of C20C activity since 1999 Phase 1 (prior to 2003): SST and sea ice changes • Hadley Centre provides HadISST1.1 SST and sea ice data set as lower boundary conditions • Integrate over 1871-2002 (at least 1949-2002) • Ensembles of at least 4 members Phase 2 (2003 - ): include atmospheric composition changes • Greenhouse gases – CO2, O3, etc. • Aerosols (volcanic) • Solar variability • Hadley Centre can provide a full set of forcings inc. HadISST almost to date. Phase 3 (2007 - 2011): “Pacemaker” experiments, much more emphasis on land surface /diurnal variation of SST/ better SST and sea ice • Land surface forcing (version already in Hadley Centre model) and special experiments • Explore influence of diurnal variation of SST in enhanced version of HadISST1 • More highly resolved HadISST2 from late 2009 based partly on the new high resolution Met Office OSTIA data set now used in NWP.

  8. BOM (Australia) COLA + GMU (USA) CERFACS (France) CNRM (France) CPTEC (Brazil) ETH Zurich (Switzerland) Hadley Centre (UK) IPSL (France) LASG/IAP (China) ICTP (Italy) INGV (Italy) MIT (USA) MRI/JMA (Japan) NASA/GMAO (USA) NIWA (New Zealand) GFDL (USA) PMOD/WRC (Switzerland) SNU (Korea) UCLA (USA) UMCP (USA) MGO (Russia) C20C Participating Groups

  9. Links to WCRP • C20C reports to CLIVAR including reports in CLIVAR Exchanges • Also reports to Working Group on Numerical Experimentation (WCRP/CAS/WGNE) • New Links to CLIVAR/SPARC.

  10. Linkage to WGSIP • WMO/WCRP Working Group on Seasonal to Interannual Prediction (WGSIP) works in C20C-related areas • develop a program of numerical experimentation for S-I variability & predictability, paying special attention to assessing & improving predictions • develop appropriate data assimilation, model initialization & forecasting procedures for seasonal to interannual predictions, considering factors like observing system evaluation, use of ensemble & probabilistic methods and statistical and empirical enhancements • advise CLIVAR SSG on the status of S-I forecasting & adequacy of CLIVAR observing system, and liaise with JSC/CLIVAR WGCM and JSC/CAS WGNE • C20C - WGSIP collaboration discussed at WCRP Workshop on Seasonal Prediction (Barcelona, Spain, 4-7 June 2007)

  11. Contributions to IPCC AR5 • C20C is well-positioned to contribute in a major way to Intergovernmental Panel on Climate Change (IPCC) AR5, anticipated in 2012-2013 • Detailed input planned at next Workshop late 2009 when IPCC AR5 will be clearer

  12. Special Topics • Predictability and understanding of seasonal to multi-decadal phenomena • 1930s drought in USA (“Dust Bowl”) • Winter NAO variations, especially since 1960 including stratospheric influences. • Autumn 2000 western European floods • 2003 European heat wave • Interannual to interdecadal variations of summer climate over Europe and North Atlantic. • Decadal modulation of responses to ENSO • Time series – variations, trends and their causes • SOI, NAO, PNA, Asian monsoon rainfall, Sahel rainfall, Nordeste of Brazil rainfall, MJO trends • Global and regional land surface air temperature trends • Others, e.g., river runoff trends • Use of new diagnostic methods in climate variability studies

  13. Key Validating Data Sets • NCEP/NCAR Reanalysis (1948-now) • ERA40 Reanalysis (1958-2002) • HadSLP global monthly sea level pressure analysis updated with modified NCEP (1850-2007) • New EMSLP daily sea level pressure data set over extratropical N Atlantic and Europe (1850-2003) • Brohan et al land surface air temperature data (1850- now) and Hulme land surface rainfall analyses (1871-1998) • Xie-Arkin global precipitation analysis (1979-now)

  14. Recently designed C20C experiments

  15. Three contrasting examples of recent C20C published papers List of contributions: http://www.iges.org/c20c/c20c_related_papers.pdf

  16. Simulating Dust Bowl era drought from Schubert et al. 2004 (Science, 19 Mar2004)

  17. Effect on the winter NAO of imposing observed stratospheric winds at 50hPa on HadAM3 Change in surface pressure Change in NAO index Model also forced with HadISST and all known major forcings in C20C mode. Full NAO and surface climate change 1965-95 reproduced From Scaife et al, 2005, GRL

  18. Secular increase in predictability of boreal winter mean temperature over land, 1897-1998, using two models mainly caused by decadal changes in ENSO variability Kang et al, 2006, GRL, highlighted

  19. Evolving C20C Experimental Design • Pacemaker • Specified SST in limited region (e.g. eastern tropical Pacific or north Atlantic) • Thermodynamic ocean (slab or mixed layer formulation with Q-flux) • Dynamical ocean models in some basins • Land Use and Change (LUC) • Coordination with LUCID • Phenomena-Focused Experiments • subsets of C20C group • West African Monsoon Modeling and Evaluation (WAMME) • Asian monsoon • Influence of the stratosphere on seasonal predictability • Use of fully coupled models for investigating near century phenomena like AMO

  20. Pacemaker Strategy: Overcoming Shortcomings of AGCMS and Coupled Models Observed Observed Pacemaker JJA Rainfall Composite (El Nino - La Nina) Pacemaker design: specified SST regions Pacemaker DJF SST Composite (El Nino - La Nina) The “Pacemaker” strategy permits a consistent air-sea energy balance while simultaneously including the time sequence of climate-driver events, such as ENSO. Teleconnections from the eastern tropical Pacific to remote tropical and extratropical regions are well represented in pacemaker runs, e.g., phenomena that are at once driven by and independent of ENSO, like the Asian monsoon. Cash et al. 2007

  21. Conceptual model for analysis of ensembles Potentially predictable, “forced” and well modelled Methodology for multi-model evaluation (Scaife et al. 2008 in prep.) YES 20th Century Climate Event (e.g. surface T trend) Consistent with ensemble means? Unpredictable internal variation but well modelled YES NO Consistent with ensemble members? Poorly modelled in this experiment: missing process/forcing NO

  22. Simulations of climate indices(Scaife et al, in prep)

  23. Simulation of Indian Monsoon Rainfall (IMR) and causes of its decadal variations – Kucharski et al in prep. Interannual ensemble means, ENSL (1902-1999; black) and CRU (red) Interannual ensemble means, ENSS (1950-1999; black) and CRU (red) Decadal IMR of CRU (red) and the ensemble means of C20C (black)

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